This application is based on Application No. 2001-354851, filed in Japan on Nov. 20, 2001, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a staring fuel injection control device for an internal combustion engine, where the fuel injection system at the starting time is improved.
2. Description of the Prior Art
In the case of performing fuel injecting to each cylinder of an internal combustion engine, it is necessary to judge to which cylinder, the injection should be performed, and therefore, the cylinder discrimination is performed, where the reference crank angle (for example, 75 degrees before the compression TDC) of a specific cylinder is discriminated. In order to perform this cylinder discrimination, it is necessary to actually operate the starter motor to rotate the crank shaft and the cam shaft of the internal combustion engine, and therefore, if the fuel injection is started for the first time after the completion of the cylinder discrimination, the completion of starting becomes late, and the starting ability becomes worse.
Therefore, conventionally, in order to improve the starting ability, in the time until the completion of the above described cylinder discrimination, the nonsynchronous injection is first performed to all the cylinders just after the start of the starting, and next, the synchronous injection is performed to all the cylinders in synchronization with the above described crank angle signal. Then, just after the completion of the above described cylinder discrimination, the above described sequential injection is started.
However, in the case of the above described fuel injection, the fuel injection is performed to all the cylinders in the state where the position of each cylinder is unclear during the time until the completion of the above described cylinder discrimination, and therefore, depending on the position, a cylinder where the intake valve is closed during the fuel injection may come into existence. In this cylinder, only part of the injection fuel is taken in, and therefore, the mixture in the cylinder becomes in the lean state, and the incomplete combustion such as lean misfire is caused, and a lot of unburned gas (HC) is discharged, and the exhaust gas emission becomes worse. Furthermore, in the cylinder where intake remainder is produced in the injection fuel, the remaining fuel which has not been taken in last time is also taken in at the next injection time, and therefore, there has been such a problem that excessive fuel is taken in the cylinder to cause the rich combustion, and the discharge amount of HC is still more increased.
The present invention is made to solve the above described problems, and it is an object to provided a starting fuel injection control device for an internal combustion engine, wherein while keeping starting ability, the incomplete combustion caused by the lean misfire or the rich combustion at the starting time can be prevented, and the discharge amount of HC at the starting time can be reduced.
The starting fuel injection control device for an internal combustion engine according to the invention includes a unit for estimating the starting ability of an internal combustion engine and a crank angle detecting unit for outputting a crank angle signal in synchronization with a specific crank angle position of each cylinder of the above described internal combustion engine. The device also includes a cylinder discriminating unit for discriminating a reference crank angle of a specific cylinder (hereafter referred to as xe2x80x9ccylinder discriminationxe2x80x9d) , a first injection unit for simultaneously injecting fuel to all the cylinders before the completion of the above described cylinder discrimination at the starting time, and a second injection unit for starting the independent injection (hereafter referred to as xe2x80x9csequential injectionxe2x80x9d) by turns for each cylinder in synchronization with the above described crank angle signal just after the completion of the above described cylinder discrimination. The device also includes a unit for stopping the above described simultaneous injection until the completion of the above described cylinder discrimination, only in the case where the starting ability of the above described internal combustion engine is estimated to be better than a specified level.
The starting fuel injection control device for an internal combustion engine according to the invention further includes a third injection unit for starting the above described sequential injection just after the completion of the above described cylinder discrimination only in the case where the starting ability of the above described internal combustion engine is estimated to be worse than a specified level different from the level to stop the above described simultaneous injection, and which simultaneously injects fuel to another cylinder where intake is possible, simultaneously with the first sequential injection.
The starting fuel injection control device for an internal combustion engine according to the invention further includes a unit for determining the period to stop the above described simultaneous injection in the time until the completion of the above described cylinder discrimination according to a previously set map.
The starting fuel injection control device for an internal combustion engine according to the invention further includes a unit for determining the injection cylinder according to a previously set map, in the case where there are a plurality of cylinders whose intake is possible other than the sequential injection starting cylinder in the above described simultaneous injection after the completion of the above described cylinder discrimination.
The starting fuel injection control device for an internal combustion engine according to the invention further includes a unit for determining the fuel injection amount independently for each cylinder according to a previously set map, in the above described simultaneous injection after the completion of the above described cylinder discrimination.